﻿#Region "Microsoft.VisualBasic::3decf2be3bd23242b3d37b2d9fde0dbb, LINQ\LINQ\Interpreter\Expressions\SymbolReference.vb"

' Author:
' 
'       asuka (amethyst.asuka@gcmodeller.org)
'       xie (genetics@smrucc.org)
'       xieguigang (xie.guigang@live.com)
' 
' Copyright (c) 2018 GPL3 Licensed
' 
' 
' GNU GENERAL PUBLIC LICENSE (GPL3)
' 
' 
' This program is free software: you can redistribute it and/or modify
' it under the terms of the GNU General Public License as published by
' the Free Software Foundation, either version 3 of the License, or
' (at your option) any later version.
' 
' This program is distributed in the hope that it will be useful,
' but WITHOUT ANY WARRANTY; without even the implied warranty of
' MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
' GNU General Public License for more details.
' 
' You should have received a copy of the GNU General Public License
' along with this program. If not, see <http://www.gnu.org/licenses/>.



' /********************************************************************************/

' Summaries:

'     Class SymbolReference
' 
'         Constructor: (+1 Overloads) Sub New
'         Function: Exec, ToString
' 
' 
' /********************************************************************************/

#End Region

Imports System.Data
Imports LINQ.Runtime

Namespace Interpreter.Expressions

    Public Class SymbolReference : Inherits Expression

        Friend ReadOnly symbolName As String

        Sub New(name As String)
            Me.symbolName = name
        End Sub

        Public Overrides Function Exec(context As ExecutableContext) As Object
            Dim symbol As Symbol = context.env.FindSymbol(symbolName)

            If symbol Is Nothing Then
                If context.throwError Then
                    Throw New MissingPrimaryKeyException(symbolName)
                Else
                    Return Nothing
                End If
            Else
                Return symbol.value
            End If
        End Function

        Public Overrides Function ToString() As String
            Return $"&{symbolName}"
        End Function
    End Class
End Namespace
